U.S. Pat. No. 4,468,233 disclosed a motor fuel containing alkyl tert-butyl ethers for increasing the octane number and decreasing the proportion of pollutants in the exhaust gas. Even this prior art can be prepared lead-free for decreasing pollutants in the exhaust, it however does not show any benefit to reduce the carbon deposit in an internal combustion system. The carbon as accumulated in the combustion system may lower the fuel combustion efficiency and engine efficiency and may also shorten the engine life.
The present inventor has found the drawbacks of the prior art and invented the present fuel composition having high octane number for enhancing anti-knocking property and also for minimizing the carbon deposit in a combustion system.